Spacer trap for rockets



May 31, 1949. c. N. HICKMAN SPACER TRAP FOR ROCKETS Filed March 2l, 1946 Patented May 3.1, 1949 SPACER TRAP EOE] ROCKETS" signor: toY the. linitedzstatesnof America: asi'repa e resented bythe `Secretary of War Application MarchV 21, 1946; S'erialNg" 656,118?

`6 Claims.:v (C1. 60.'-.35.6) 'y The invention describedhereinmay be manufactured and `used by or for the Governmentior governmental purposes,` without the payment to me of any royalty thereon.

This invention relates to rocket projectiles and more particularly to an improved method for supporting and trapping propellentpowder grains within rocketmotors.

It is a principal object of thiscinvention to provide `an improved powder-` supporting and separating means for use with trap wire assemblies which will give venting .space between the grains and at the same time transfer the drag and setback forces on each grain'directly to the trap wire uponwhich it i-s strung insteadof down the column of powder.

Another objectof thisfinvention is to providea powder trapping device which strengthens and holds together a cage type multiplewire powder trapping assembly, and which is easily assembled with and on the said `multiple wire trapping means.v

A still further' object of the invention is to provide` a relativelysimple powder" spacing trap device which is locked in its proper -position on a trap wireor rodV throughout the burning of the propellent grains andthe forward. acceleration of the rocket motor resulting therefrom:

Additional objects, advantages and features. of invention reside in the` construction,arrangement and combination of partsinvolved inthe embodiment of theinvention, as will be understood from the following .description ,and accompanying drawing, forming part of the specification, Wherein similar numbers are `used to designate likeparts throughout the specification-and` drawing, l

In the drawing:

Figure 1 is a partial longitudinal section of a rocket projectile provided with a trap assembly constructed in accordance with my invention,

Figure 2 is an enlarged plan View of one of the spacer trap washers shown'in Figure 1,

Figure 3 is a transverse ysection of a spacer trap washer taken on the line 3-3 of Figure 2,

Figure 4 is `a plan viewof `a modied form of the spacer trap washer' shown in Figure 2,

Figure 5 is a transverse section of the modied trap washer, taken on the line 5--5 of Figure 4,

Figure 6 is a partial' longitudinal section through the ends of adjacent powder grains strung on the same wire, illustrating the embodiment of` the modified form of trap `washer in the trap assembly,

Figuren is` a longitudinarview,` partly in. sec.-

2: f tion, of a. mcdiiezjormrof trap...washer for. use with a singletrap. wire,',and, 1Y

Figure 8 i-s a plan view ofthe trap washer shown in Figure 7.

Referring to` the..dravvi'ngl` and. particularly to Figure` 1, the. numeral lillv designates generally ane assembled. rocket.. projectile havingla fuze. LI, a shell 1,2,` and a.motoxmbodi/13;y The shell. lf2 includes Aa hollowbody lllfanda hurster tubel I 5, both of which are `iilled with ahighexplosive-bursting. chargeM which is. detonated by` the..fuze. Il. The motori-tbody` [3.consist`s-of hollow steel tube which is constricted near its rrearvvardor tail .end to form a. nozzle 1.6 through.. which `the .propellent gases ,from within. the, motor, bodyfare discharged at a relatively,.higlfrvelocityA to propeLtl-iefrocket forwardlytowardthaiobject .atlwhich it is aimed..

The said-.motorbody isinternallythreaded at its forward end `for the..reception of. the correspondingly threaded.rearwardendof the.shell.l2, and an annularsafetygrooye.1.1;' isprovided near its forward end to permit itlto separate` at a .denite` point, should. an.l excessive. pressure.. be generated withinthesaid. motorbodnuponring.. The noz- .z1eportionv IB. maybeiarrangedrfor the attachment` of foldinglnss: lwtostabilizethe rocket yin flight. f f An. electrically. controlled .igniter 35 and igniternbags` 36 areprovidedlfor igniting; the pro.- pellentcharge.,

The propellent chargeis-securedwthin amotor chamben I8. formedbyLthawallsof .thesaid motor` body. I3; .It consistent. aplurality of cylindrical powdengrainsblq;` Whicharestrungon a plurality vtof traprod's. or:` wires 2l) y suspendedlfrom a trap washer..2 l=whichrestson an annularshoulder 22. formed. about innencircumierenceof the motor. chamber l 8.. Theftrap..washer 2l is` provided. witha pluralityofopenings?3=large enough to f permit. passage of, the trap rods.12ll but .which will retain.. the beaded. headstMt formed-on the saidrtrap rods, `thesaidnpenings.beingso arranged that the suspended rods:` formt a. cylindrical cage. An. annular. groove 2,51 fis` provided ,in the base of theshell.. I2. to` receive. the, ;beaded heads. 2liwhenthe shell;isQattachedtothe motor body...

The trap wires 2D"are upset along their. .lengths at points between. theends. of adjacent powder grains I9 andatthebottomaofl the lowest .powder grains, to forman'ges or nubs 25.2 Spacer. trap Washers or ring ,members` 21." are.` assembled; over the nubs 26 `to space the powder.grainsv IQ from each other...` The..'outerl edges .lof the .ring mem-` ber 21 areturned rearwardly'to the plane of, the washer t0 l engagez.the/outertportion of.' the 'nubs 2li,."t,`te'll'ely` provdin'gjretaining" means` for preventing the trap wires ZIJ from moving radially outward and away from the ring member 21 after the trap and powder grains are assembled. The ring members are also provided with a plurality of radial slots 28 extending inward from the outer periphery and having a width such that, the slot will receive the normal diameter of the trap wires 2t but will not allow the nubs 2t to pass therethrough. The cross-section of the WasherI 21 may be C shaped, as shown in Figure 3. In other words, the ring may be inthe form of half a hollow tore divided normally to its axis of generation.

The modied spacer washer 29 shown in Figures 4, 4and 6 is generally similar to the washer 21 except that portions of the outer edge have been cut away to provide a washer of lesser weight. The outer turnedvedges of washer 29 interlock with nubs 26 on the trap wires 20 in the manner shown in the construction illustrated in Figure 6, to prevent separation of the trap wires 20 from the Washers during the burning of the powder grains i9.

The modification shown in Figures '1 and 8 are primarily intended for use when the propellant may take the form of larger diametered powder grains 30 strung on a single trap wire 3l. A slotted spacer washer 32 having an annular recess 33 in its rearward face engages the nulo 314 and is locked in place on the said trap wire by the pressure of the powder grain 36 and the iiowing of combustion gases thereagainst during acceleration of the rocket.

In the construction illustrated and described herein, each individual powder grain is positively supported against rearward movement with respect to the trap wires during acceleration of the rocket due to the burning of the grains. Likewise, the individual grains are spaced from each other by the novel trap members disclosed. The edge construction of the ring members 21 and 29, and the annular recess in the member 32, are provided to prevent the said members from becoming detached or separated from the nubs formed on the trap wires during the burning of the powder grains, and the said members 21, 29 and 32 are not large enough to impedethe ilow of combustion gases to the nozzle of the rocket. It has been found that the use of the improved spacer trap construction herein disclosed results in relatively easy assembly of the powder grains on the trap wires, and in improved motor performance.

It will be understood that, in all species, the maximum diameter of nubs or flanges 34 is .a little less than the diameter of the axial holes through the powder grains, so that assembly is eiected by Stringing the grains onto the respecvtive wires and then inserting a ring member or washer, such as 21, behind each set of grains until each trap wire is received in its corresponding slot. The entire trap and propellant assembly is then inserted into tube I3 until washer 2l rests upon shoulder 22. Thereafter, the uze and burster tube assembly may be screwed into place to hold the trap and propellent grains in position in the tube.

The form of my invention herewith shown and described is to be taken as a preferred example of the same, and various changes in the shape, size and arrangement of parts may be resorted to without departing from the spirit of the invention or the scope of the subjoined claims.

Having thus described the invention, I claim:

l. In a rocket motor assembly having powder grains strung on a trap wire, the said trap wire being provided with a plurality of spaced nubs intermediate its ends, a spacer member for positioning on said wire between the ends of said grains, said spacer member having a slot therein to receive said trap wire and having retaining means adjacent said slot to engage with a nub on the said trap wire.

2. In a rocket motor assembly having powder grains strung on a plurality of trap wires, each of the said trap wires being provided with a plurality of spaced nubs intermediate its ends, a spacer member for positioning on the said trap wires between the ends of the said powder grains, said spacer member having a plurality of slots therein to receive the said trap wires respectively between a nulo and the adjacent rearward end of a corresponding powder grain, the outer edge of the said spacer member being turned rearwardly along said trap wires for engagement with the nubs thereon.

3. In a rocket motor assembly having powder grains strung on a plurality of trap wires, each oi the said trap wires being provided with a plurality oi spaced nubs intermediate its ends, ya ring shaped spacer member for positioning on said wires between the ends of the said powder grains, said member having radial slots extending inward from its outer edge to receive said trap wires, the outer edge of said spacer member being turned rearward of the plane of said member for engagement with the nubs on said wire.

4. In a rocket motor, means forming a generally cylindrical motor chamber, a plurality of powder grains in said chamber, a trap wire extending longitudinally through said chamber passing through axially extending holes in said grains, a plurality of spaced nubs iixed on said wire, a plurality of washers each having a slot embracing said wire and of less width than said nubs, each washer being interposed between a nub and the rear end of a respective powder grain whereby each grain is individually supported on said wire by its washer, each said washer having a recess therein on its rear side extending about the closed end of the slot therein, each nub tting within a respective recess to thereby lock each washer against laterally displacement relatively to said wire. i

5. A rocket motor comprising means forming a generally cylindrical combustion chamber, a plurality of circumferentially spaced trap wires extending longitudinally through said chamber, each said wire having a'plurality of spaced flanges fixed thereon, means iixing each wire at its forward end in said chamber, each ilange being in substantially the same plane transversely of said wires with a corresponding flange on each of the remaining said wires, a plurality of propelling powder grains on each said wire, and a plurality ci washers each having radial angularly-spaced slots therein of less width than the diameter of said ilanges, each slot embracing a respective wire between a iiange and the adjacent rearward end of a powder grain whereby each said powder grain is supported on a flange through the intermedia-ry of its washer, each slot in each washer terminating in a rearwardly-turned edge whereby, when a washer is resting .on its anges, radial movement of a wire out of its slot, is prevented by said edges.

6.v A rocket motor comprising means forming a generally cylindrical combustion chamber, a plurality of circumferentially spaced trap wires extending longitudinally through said chambeneach said wire having a plurality of spaced anges mediary of its washer, each said washer being l0 Number 6 in the form of half a, hollow tore divided normally to its generating axis.

CLARENCE N. HICKMAN.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Name Date 2,404,190 Pope July 16, 1946 2,405,415 Eksergian Aug. 6, 1946 

